This application is based on Japanese Patent Application No. 9-300460, filed Oct. 31, 1997, the content of which is incorporated by reference.
The present invention relates to an image display unit, computer system, and image signal output control method in which an inputted image source is converted into an image signal for an external display or a TV image signal, and the converted image signal can be output.
In recent years, various multimedia computer systems have been developed along with advances in computer and multimedia technology. A computer system of this type has a function of reproducing video data and audio data in addition to text data and graphics data.
With the development of multimedia computers, DVDs are recently receiving a great deal of attention as new storage media in place of CD-ROMs. One side of one DVD-ROM medium allows to record 4.7-Gbyte data, which is about seven times larger than data on a current CD-ROM. Two sides allow to record 9.4-Gbyte data. Using such a DVD-ROM medium enables to reproduce the title such as a movie including a large amount of image information on a computer with a high quality.
Recently, portable, space-saving, battery drivable notebook personal computers are replacing desktop computers as home and office computers. Such a notebook personal computer also requires the above DVD-ROM drive unit.
When a title recorded on a DVD is to be reproduced on a notebook computer, data read by a DVD-ROM drive unit is stored in the main memory of the computer, and then transferred to an MPEG2 decoder. The MPEG2 decoder descrambles the data to cancel scrambling performed for a coded video data stream in order to prevent illicit copying of a title. The MPEG2 decoder decodes and expands the coded video data stream. The decoded video data is displayed on a notebook computer display monitor such as an LCD. At the same time, the decoded video data is converted into an analog image signal for an external CRT display or a TV analog image signal, and the converted analog image signal is externally output.
In this manner, the analog image signal is output to an external image unit such as a CRT display or a TV regardless of whether the image source requires a copy protect. Using the analog image signal allows illicit copying of an image source requiring a copy protect such as a DVD title.
In recent computers, a higher-speed CPU and an improved display controller realize advanced graphics processing such as three-dimensional graphics processing even in a personal computer such as a notebook computer. Graphics data can interactively change a display image in accordance with the user operation so as to allow the user to freely scroll on the display. Accordingly, demands arise for realizing new entertaining images by synthesizing computer graphics data and natural video data by MPEG2 and displaying the synthesized data by a display controller.
In this case, an analog image signal for an external image unit such as a TV must be generated on the display controller side. This analog image signal also requires an illicit copying prevention measure.
It is an object of the present invention to provide an image display unit, computer system, and image signal output control method in which output of an image signal for an external image unit can be controlled in accordance with the type of image source and the type of input device, and illicit copying of an image source requiring a copy protect can be prevented.
To achieve the above object, according to the present invention, there is provided a computer system, comprising: means for inputting an image source; means for displaying the inputted image source on a flat panel display; means for converting the inputted image source into an image signal for an external display or a TV image signal; means for outputting the converted image signal externally; determining means for determining whether or not the image source requires a copy protect; and image signal output control means for inhibiting the output means from outputting the image signal for the external display or the TV image signal externally.
In this computer system, for example, when a copy-inhibited source such as a DVD title or a digital satellite broadcast is inputted, output of an image signal for an external display or a TV image signal is inhibited. The image source is displayed on only a dedicated display monitor constituted using a flat panel display such as an LCD.
In general, a display signal on the flat panel display is digital data using a dedicated interface. In a notebook computer, the flat panel display is mounted on the computer main body. A display signal on this flat panel display is not externally output. It is therefore difficult to illicitly copy an image source using the display signal on the flat panel display in practice. An image source can be prevented from illicit copying.
The computer system of the present invention further comprises a decoding unit for decoding a digitally compressed and coded video signal, a first TV signal converting means for converting the video signal decoded by the decoding unit into a first copy-protected TV image signal and for outputting the converted signal, a display control unit for controlling a display monitor and capable of displaying on the display a synthesized image signal of the video signal decoded by the decoding unit and graphics data written in an image memory, and a second TV signal converting means for converting the image signal obtained from the display control unit into a second TV image signal and outputting the converted image signal. When the image source requires a copy protect, or the image source is read by a drive unit which can read the image source requiring a copy protect from a storage medium, the image signal output control means switches the TV image signal to be output externally from the second TV image signal to the first TV image signal which has been copy-protected.
In this arrangement, as for an image source not requiring any copy protect, an entertaining image can be output to an external TV by the second TV image signal which can be synthesized with graphics data. When an image source requiring a copy protect is to be displayed, or a video signal read by a specific input device such as a DVD drive is to be displayed, the TV image signal to be output externally is switched from the second TV image signal to the first TV image signal which has been copy-protected. By controlling output of the TV image signal in accordance with the type of image source and the type of input device, an entertaining image can be displayed by synthesizing video data and graphics data, and at the same time a copy protect can be achieved.
According to the present invention, output of an image signal for an external image unit can be controlled in accordance with the type of image source and the type of input device. An image source requiring a copy protect can be prevented from illicit copying. Particularly in a notebook computer, only output of an analog RGB signal for an external CRT display or a TV analog image signal can be inhibited, while a display monitor constituted by, e.g., an LCD maintains the display. Therefore, illicit copying can be efficiently prevented.
Additional objects and advantages of the invention. will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.